Abstract：The effects of initial water content in soil on the soil moisture distribution during bubble irrigation were investigated using repacked soil boxes. Five initial soil Moisture content were tested. The results showed that the initial soil moisture content has less influence on the shape of soil wetted volume but quite large on the volume sizes under the condition of bubbledroot irrigation. The time needed to wet soil surface was reduced and the expansion of the wetting front became fast horizontally and vertically with increasing initial soil moisture content. The higher the initial moisture content, the more uniform the distribution of soil moisture in a wetted soil volume. Empirical equations were fitted with the experimental data to estimate the surface wetted radius, maximum horizontal wetted radius and vertical wetted depth. The IRE and the RMSE between prediction and observation were 0.63%, 0.4%, 083% and 0.59%, 0.12%, 0.73%, respectively, suggesting the empirical equations are applicable for estimate of soil water infiltration parameters in bubble irrigation.
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